Process for making anhydrcus zinc chloride



June Z9 1926.v

, ig@ N. c. cHRls'rENsl-:N I

PROCESS FOR MAKING NHYDROUS ZINC CHLORIDE Filed June v. 1923 n longugw Y 2dr', i926.

NXELS G. UHRIETENSEN, OI@

Application led June "f,

This invention relates primarily to the manufacture of anhydrous zinc chloride and the recovery of lead fromlead chloride and secondarily to the manufacture o'ffciiustic alkali and also to the refining of lead bullion., 'As is well known to chemists and metri llurgists, the manufacture of anhydrous cinc chloride :troni Zinc chloride solutions is e delicate and rather difficult operation because of the tendency of the zinc chloride to breek up into zinc oxide and hydrochloric acid and to l'orn'i oxychlorides upon evapn oratie-u of the Zinc chloride solution. lt is also 'Well known that for many purposes the presence of zinc oxide in the zinc chloride is very deleterious.

li 's the object ol iny invention to provide af simple cheap and ellicient inethod oi. inanutacturing anhydrous zinc chloride, free from the ordinary difficulties encountered in evni'iornting solutions, und to produce a zinc lchloride free from zinc oxide 0r oxycliloride.

lt is also the object of niy invention to recover the lead from lead` chloride mede in the treatment of lead ores and metallurgical products by the chloride process described in nlyA Patents Nos. 1,434,085, lflelldlol, 1,4i-r1, w ifiince, 1,435,891, meiner, issue i, 1,415,796, License, 1,539,711, 1,539,712, 1,539,213 mi 1,539,714.

rlt also the object of my invention to provide u combined method ot' inenufzrcturiner anhydrous zinc chloride and caustic alkali, and also to provides. simple combined method el manufacturing anhydrous zinc chloride und caustic zillrali and at the saine tiine refining lead bullion.

My process is simple in operation requin ing no. extreme conditions of temperature or pressure or special protection against corrosive gases, and has e very high ellicleney in that a practically complete conversion and recovery of the chemicals used inay readily he secured. The simplicity and elliciency ol' the operation is such that comparatively simple apparatus may be used.

ly process consists in general of heating` dry lend chloride with metallic Zinc and separatingr the anhydrous zinc chloride fron'i the lead toi-ined by this treatment. The operation is preferably carried out by heating the dry lead chloride until it melts thus driving oil' all traces ol? moisture and then adding, ihn metallic zinc either in the solid forni or in e molten condtion.-i The zinc 19%. Serial; We. 5d.'

displaces 'the lend .in the chloride :forming inolten anhydrous eine chloride and molten metallic lead as indicated in the 'following chemical equation:

Phill, efdnzZnClz-klb.

containing acid or i rric chloride acts very readily on onion/.ed ores of lead and. also readily on sulphide ores of lead dissolving the lead as a chlorn e in the brine. .l'ie methods olf treating l id ores for the reco-fery' oi? the lead as e nfide is described in rny Patents lios. i,flldl. 2,390,603, nieuwe.. Liz-lense, #1,342,085, helices,

lfllldlljl, hield) o und lflll, und patent appl.' s QLdOO, 330,320, 329,333 and ,$91. The method l prefer to use is that ol' dissolving,l the lead out of the ores 'with a b, Ve containing;- hydrochloric acid in suilicent quantity to react with 'the lead mineral in the ore sind il'orin l'bClz, as the product nuire easily secured :1s pure lead chloride when llC-l is used their when H230, or lleCl3 :ire used to dissolve the lead. lf the ore treated is a sulphide the pregnant solution should have ull the. H25) reinoved by boiling or by passing air through the solution, betere cooling and precipitating the lbClZ, so :is to avoid the carrying of any sulphide intothe process for the nlanuliacture 0l the ZnCl2.

The Phill, may also be made by the dis solving lead chloride troni volatilizing processes in a hot brine and precipitaiup,- by cooling', il; may also bel inode by dissolving scrap-lead such as battery plates and other loiins of scrap in a hot acid brine and cooling as described for the treatment of ores, as the metallic lead dissolves readily in s. hotl acid brine.

The' lead chloride may also be made in connection with the manufacture et caustic :essonne tion up 'to between :nul 7l/3%. This regiment lead solution flowing troni the cell is cooled und the lend chloride precipitated so that the cold solution carries Jfrom 11%% to 2% Pb. rlhis cold solution is heated practically to boiling und returned to the cell again through the inlet channel (11, 11). As the formation of the lead chloride :it the snode gei'ierulfes un E. ll. l?. of apnroimutel. lo `Jolts thisl cell opere-.les with pproxinietcly ne hnlt the power consump tion ot the ort' try caustic simili-chlorine cell. its the lezul--hrine circuit is continuou.y cuen'iented by the small amount ot brine passing' into the :inode compartment tlnough the dieloluugni. the leed must be precipitated from. e portion ot this solution :it intervals with hluUH and the PMOHM seperated from the brine and treated with HCl and returned to the hot leed brine and the purified brine used over again. The horizontal type ot' cell shown in Fig. lille my preferred type es the specific gravity of the solutions formed in the cell are such that the naturel 'flow ot solution through the cell is in the direction desired.

As will readily be seen this cell and procinny he used for the refining et leed hnli es in ordinzufy electrolytio reiinil'lg', the leed being' covered from the pure chloride formed hy treatment with inetallic zinc as described. In this ense the combined process otnmaking the leed chloride and zinc chloride would have the following final .rcdnctsz enhyi'lrous ZnCh, NaOH, H, und refined Pb. ln case the cell is not used for refining the molten lend from the ZnCh, uuinufucl'ure is cast into modes and used over again inY the process. in ull my methods of melting lhtlg except the last defcribed ce stil: cell method either u sodiur ehloride"or czilciinn chloride solution brine-muy be used und by the term brine u in the claims l ineens either u. concentrated sodium chloride or calcium chloride solution.

The lend chloride made by :my ot the methods indicated ubovc is w: il' l tree from contaminating .sells und thoroughly dried. llt is then melted preferably in n neutral etruosphere lo prevent the fornmtion ol" any lead city/chloride und n'fetellic Zinc is added to the molten lend chloride in the proportion required to cli-compose the leed chloride und form anhydrousv zinc chloride which in u. molten condition und is readily poured oil' the mollen ineiullic lend which' formell. This operation is gireicrably carried out. in :i fused-silica Vitrossil retort externally heet. Other materiel nur): be fused for the retort but in order to avoid contamination of the ZnCl2 and on. ucc'ount of its heet re sisting qualities li have found vitrosil to he the most suitable' materiel.. iron or copper lion by usingy the hullion in the unodes retorts may he used but are slightly acted upon by the fused PhCl2 and for that reason are not Well suited for the purpose. Porceluin and graphite crucihles here been tried but the former is eusily broken in heating and handling end the hitler is slightly permeable to both the PhCh und the AlCl3 so that neither ure Well suited to the purpose. rlhe retort should preferubly he nir tight so es to avoid slight oxidation ot the leed chloride und decomposition ot the Znt'llz which occur it' much air is iulniitted during the heating.

Frein the foregiiing tt will he eiiujiurent that my process constitutes e simple und valuable .method ot manufacturing' anhy drous Zinc chloride und et the suine time re.- covering the lead from leed chloride formed in the treatment of ores by leaching with chloride solutions. lt will also he apparent that my process constitutes n simple and valuable method of manufacturing anhydrous zinc chloride and at the same time recovering leed from scrap metal such us batteryplates and other forms of-scrap lead. llt will also loe apparent that my processes constitutes a simple and valuable method of innuntacturing enhylflrous zinc chloride und et. the saine time .manufacturing caustic sode und hydrogen. lt will also be x@purent that my process constitutes u simple und valuable method ot manufacturing anhydrous zinc chloride und at the sume time refining lend bullion and .manufacturing caustic soda and hydrogen.

As will he clear to ull engineers engaged in the metallurgical. iield, it is .impossible to give ell the minute details of practical opern ation of the dillerent parte' of my process or all the details of construction of the nppuretus used und l dornot therefore desirev te ce limited by the 'lore ne; .necessarily hriet` description except es interpreted in the clnims, though the foregoing iilescription is limpie to multe the invention und itsprecticnl use elettr "to ell engineers or metallurgrists :tm'niliur with the metallurgical and chemical practices involved in similar end related operntions. l

Having described my process, what it claim und desire to patent is:

l. The process ol nmking' anhydrous Zinc chloride which consists in heating dry lead chloride together with metallic zinc whereby anhydrous zinc chloride and metallic lend :1re formed.

The process ot making' anhydrous zinc chloride which consists in heating dry lead chloride together with metallic zinc, and thereby redufing the lead chloride end forming metallic leed und anhydrous zinc chloride. i

The process of making enhydrous zinc chloride which consists in heating dry leed chloride together with metallic .eine stiere- 'lill lili icc

by metallic lead and anhydrous zinc chloride are formed, and separating said molten zinc chloride from the melted lead formed.

4. The process of'making anhydrous zinc chloride which consists in heating dry lead chloride together with metallic zinc, and thereby reducing the lead chloride and forming metallic lead and anhydrous zinc chloride and separating vsaid molten zinc chloride from the molten lead formed.

5. The process of making anhydrous zinc chloride which consists in adding metallic zinc to molten lead chloride whereby molten metallic lead and molten anhydrous aluminum chloride are formed.`

6. The process of making anhydrous zinc chloride which consists in adding metallic zinc to molten lead chloride and thereby reducing the lead chloride and forming molten metallic lead and molten anhydrous aluminum chloride, and separating said molten Zinc chloride from said melted lead.

7 The process of makihganhydrous zinc chloride i'vhich consists in dissolving metallic lead in a hot concentrated brine by using metallic lead as the anode of a double diaphragm caustic alkali cell substantially as described and forming a hot concentrated lead chloride solution, cooling said concentrated lead chloride solution and precipitating lead chloride therefrom, separating said lead chloride from said brine, drying said` lead chloride, heating said dry lead chloride together ,with metallic zinc and forming nietallic lead and anhydrous zine chloride and using said metallicl lead over a ain in the anode material of said cell in s'ai recess.

8. The process of making anhy reus zinc chloride which consists in dissolving metallic lead in a hot concentrated brine by usin lead bullion as the anode of a double diap ragm caustic alkali cell substantially as described and forming a hot concentrated lead chloride solution, cooling said concentrated lead chloride solution and precipitating lead chloride therefrom, separating said lead chloride from said brine, dr 'ing said lead chloride, heating said dry lea chloride together with metallic zinc and forming' molten metallic lead andmolten zinc chloride, and separating said zinc from said molten lead.

9. The combined process of making caustic alkali, hydrogen, and anhydrous zinc chloride which consists in using metallic l5.7

lead as the anode in a double diaphragm caustic alkali cell substantially as described and thereby making caustic alkali, hydrogen and lead chloride, and heating said dry lead chlorideI together with metallic zinc so as to form anhydrous zinc chloride and metallic lead, and using said metallic lead over again in the anode material ot' said cell in said process.

NIELs c. cHRIs'rENsEN.

KSG 

